You need to generate these yourself, typically by writing code. There's a number of ways of simplifying this process though, once of which is by using Temboo.

Temboo makes it easy to work with APIs, and that means simplifying the OAuth process. You can use the Temboo's OAuth Wizards to generate a Facebook access token without writing any code. You can also move beyond the Wizards to generate both tokens and authorization URLs using code that Temboo will automatically generate for you in the language of your choice, including PHP.

Check out the videos here to learn more about how Temboo can help with OAuth: